1. Field of the Disclosure
The following relates to abrasive articles for use in machining and more particularly use of foamed abrasives in machining processes.
2. Description of the Related Art
Abrasives used in machining applications typically include bonded abrasive articles and coated abrasive articles. Coated abrasive articles generally include a layered article including a backing and an adhesive coat to fix abrasive grains to the backing, the most common example of which is sand paper. Bonded abrasive tools consist of rigid, and typically monolithic, three-dimensional, abrasive composites in the form of wheels, discs, segments, mounted points, hones and other tool shapes, which can be mounted onto a machining apparatus, such as a grinding or polishing apparatus. Such bonded abrasive tools usually have three phases including abrasive grains, bond material, and porosity.
It has been shown that certain amounts of porosity within bonded abrasive structures can improve machining efficiency and protect the quality of the workpiece being machined from thermal or mechanical damage. However, manufacturing limitations and mechanical property requirements (e.g., strength) restrict the percentage of porosity, which is further dependent on the size of the grit, the presence of agglomerated abrasive grains, and the type of bond material.
Manufacturing techniques include use of pore formers, such as glass bubbles, organics, and the like in the bonded abrasive formation, since the natural porosity resulting from regular packing of the abrasive grains is generally insufficient to achieve high porosity. However, such pore formers tend to form closed pores and not the open porosity suitable for improving machining efficiency. In fact, the creation of excessive closed porosity can increase the machining forces necessary for effective material removal and increase the thermal damage to the workpiece. Moreover, the use of certain pore formers can require a subtractive process in which the pore formers are “burned out” of the abrasive article during forming, which gives rise to other manufacturing obstacles.